Roles of Hydrogen Donors and Organic Selenides in Inhibiting Solid Deposits from Thermal Stressing of n-Dodecane and Chinese RP-3 Jet Fuel

Abstract

Use of hydrocarbon fuels as coolants for future high-Mach aircraft is challenged by the formation of carbonaceous deposits during thermal stressing at high temperatures (>500 °C). Three hydrogen donors, tetralin (THN), R-tetralone (THNone), and benzyl alcohol (BzOH), and two organic selenides, diphenyl selenide (Ph 2 Se) and diphenyl diselenide (Ph 2 Se 2 ), as well as their mixtures, are selected as thermally stable additives to inhibit the deposition from the thermal stressing of n-dodecane and Chinese RP-3 (No. 3 jet fuel). It is found that the amount of solid deposits from thermal stressing of RP-3 is reduced by 77.0% with the additive of Ph 2 Se 2 /THN/THNone. The carbonaceous solid is further characterized using temperature-programmed oxidation (TPO), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). It is revealed that hydrogen donor THN/THNone and organic selenides possibly reduce the carbon deposits through retarding the thermal cracking rate, blocking surface catalysis, and depressing reactivity of sulfur with the surface metals, as well as their synergistic effect. The morphologies of deposits also dramatically change after adding organic selenides or hydrogen donors.

Heat-Sink Enhancement of Supercritical Methylcyclohexane Cracking over Lanthanum-Modified Beta Zeolite

“…To achieve higher heat sink, chemical reactions of endothermic fuel can be used to further enhance the heatsink potential by adding catalysts [5]. In addition, the actual chemical heat sink from thermal cracking is far behind the cooling demands due to the large amounts of methane formed at high temperature when the speed of aircraft reaches supersonic or hypersonic regimes [6,7]. Catalytic-cracking reactions can generate much smaller heat absorbents, such as low-carbon alkenes, and obtain the same gas yield as thermal cracking at a lower temperature, providing a more adequate heat-absorption capability.…”

Preparation and Anticoking Performance of MOCVD Alumina Coatings for Thermal Cracking of Hydrocarbon Fuels under Supercritical Conditions

“…21 Similarly, Guo et al reported that hydrogen donors and organic selenides possibly have a synergistic effect in inhibiting coking formation by retarding thermal cracking and reducing both the thermal oxidative and pyrolytic carbonaceous deposits caused by surface catalysis. 22 In addition, Eser et al observed that solid deposits were reduced by nearly 90% in a silcosteel reactor relative to that in stainless steel 316 tubes during supercritical thermal stressing of JP-8 (500°C and 3.4 MPa, 1 mL/min for 5 h). 19 Ervin et al found that pyrolytic Industrial & Engineering Chemistry Research ARTICLE deposition was eliminated above 90% in silcosteel during supercritical thermal stressing of Jet A (400À700°C and 3.89À6.31 MPa, 32 mL/min for 4À8 h) and that the formation of pyrolytic deposition was less sensitive to pressure on treated tubes relative to untreated stainless steel tubes.…”

Comparison of the anti-coking performance of CVD TiN, TiO 2 and TiC coatings for hydrocarbon fuel pyrolysis

“…In order to evaluate the anti-coking performance of the TiN, TiO 2 and TiC coatings, RP-3 Chinese jet fuel, comprised of 57.72% of n-paraffins, 18.56% of isoparaffins, 15.20% of cycloparaffin and 8.52% of aromatic [24], was cracked in un-coated and coated SS304 tubes which carried out in a self-made supercritical cracking device. Fig.…”